Devices of this type form an essential component of modern engine controllers, because the combustion chamber pressure must be detected very precisely, in particular for the purpose of reducing emissions. Devices are known from the related art, which have predominantly been developed for diesel engines.
Thus, for example, International patent application WO 2006/089446 A1 discusses a component for power or pressure sensors, in particular for installation in a glow plug. The component includes a measuring element in the form of a disc or perforated disc made of piezoelectric material and electrodes in the form of perforated discs or discs, which press against the measuring element on both sides, having contact points for the contact to lines. Furthermore, one or more transmission bodies situated on both sides outside the electrodes are provided. The described elements are held together by an external, electrically insulating film, for example shrink tubing, so that a sensor module is formed. The shrink tubing is used, on the one hand, for electrically insulating adjacent components and, on the other hand, for holding together the individual components of the sensor module, in particular during transport between individual manufacturing stations, until final assembly is performed.
During manufacturing of combustion chamber pressure sensors which are suitable for mass production, and which are usable as stand-alone combustion chamber pressure sensors, in particular for gasoline engines, known design and manufacturing concepts may cause technical difficulties, however. Thus, for example, the shrink tubing approach discussed in International patent application WO 2006/089446 A1 is predominantly suitable for cylindrical components. Square or polygonal piezo-quartzes may not be ideally fixed using this approach, however. Furthermore, in many cases assembly of a sensor module with subsequent transport is not necessary, because complete final assembly may be performed in one factory. Transport safety of the sensor module is thus no longer an issue in many cases, but rather recedes during manufacturing behind the comparatively complex handling steps in the event of the shrink tubing.